Apparatus for manufacturing reclosable bags utilizing zipper tape material

ABSTRACT

The present invention overcomes the shortcomings of the aforementioned prior art devices and meets the afore-mentioned needs by providing an apparatus and method for accurately sealing a multi-purpose reclosable zipper strip to a web of flexible film in an airtight manner. Moreover, the inventive apparatus and method is capable of repeatedly performing the steps necessary to seal the multi-purpose reclosable zipper strip to the web of flexible film with high manufacturing throughout and low cycle times. Generally, the apparatus and method utilize the multi-purpose reclosable zipper strip having airtight splotch seals fused in a series along desired lengths of the zipper tape. The multi-purpose reclosable zipper strip is dispensed through a feeding mechanism and, when an optical sensor detects one of the splotch seal portions of the multi-purpose reclosable zipper strip, a desired length of multi-purpose reclosable zipper strip is advanced over an elevator platform. A knife is then signaled to descend and sever the advanced portion of multi-purpose reclosable zipper strip, which is thus deposited onto the elevator platform. As the selected portion of the multi-purpose reclosable zipper strip is being positioned and deposited onto the elevator, the web of flexible film is being positioned above the platform. A sealing head is then positioned over the web of flexible film, while at the same time the elevator platform is driven upwardly so that the multi-purpose reclosable zipper strip portion positioned thereon comes into contact with the web of flexible film. The heat passing through the web of flexible film from the sealing head is sufficient to seal the peripheral portions of the multi-purpose reclosable zipper strip section to the web of flexible film, thereby creating an airtight seal between the multi-purpose reclosable zipper strip portion and the web of flexible film.

This is a divisional application based on and claims priority from U.S.Utility patent application Ser. No. 10/039,527, filed Nov. 7, 2001.

FIELD OF INVENTION

The present invention relates to an apparatus and method for sealingzipper tape to a web of flexible film in an airtight manner.

BACKGROUND OF THE INVENTION

The popularity of reclosable zipper fasteners has created a demand for alarge number and wide variety of reclosable bag sizes and types. It iscommonly known in the art to form a reclosable bag 10 through theaddition of a zipper strip 420 to a pair of bag walls 22, 24 in order toform the bag 10 with a reclosable, airtight seal as shown in FIG. 7.Transverse application of such zipper strips 420 to a web of flexiblefilm (such as a web of plastic material) is also known in the art.

In many reclosable bag applications, an airtight seal is necessary inorder to maintain the freshness and integrity of items stored within thebag 10. However, presently available reclosable bags do not provide ormaintain an airtight seal due to air leakage through the ends of thezipper strips, leakage through the seal between the strip and the web,or leakage through the interlocked fastener profiles of the zipperstrips themselves. There is thus a need for an apparatus and method forsealing a zipper strip to a web that reduces or eliminates theaforementioned leaks. There is also a need for an apparatus and methodfor repeatedly and quickly sealing zipper tape to a web to allow forhigh-speed production of a web with pre-installed zipper-tape to makethe production of reclosable bags commercially viable.

Commonly known methods of construction and seal formation often causeinaccurate, commercially unacceptable seals that cannot be produced onan economically practical scale. Commonly known zipper strip formationmethods require multiple sealing devices, precise machinery or extensiveretooling to alter the size and type of reclosable fastener. Examples ofsuch devices and methods are described in U.S. Pat. No. 5,601,368(Bodolay), U.S. Pat. No. 3,847,711 (Howard), U.S. Pat. No. 5,461,845(Yeager), U.S. Pat. No. 4,241,865 (Ferrell), U.S. Pat. No. 4,335,817(Bahr), U.S. Pat. No. 4,909,017 (McMahon) and U.S. Pat. No. 5,024,537(Tilman). None of the foregoing devices and methods satisfy the need fora multi-purpose reclosable zipper strip that can be accurately andeconomically sealed in an airtight manner to a web of flexible film.

BRIEF SUMMARY OF THE INVENTION

The present invention overcomes the shortcomings of the foregoing priorart devices and meets the afore-mentioned needs by providing anapparatus and method for accurately sealing a multi-purpose reclosablefastener zipper strip to a web of flexible film in an airtight manner.Moreover, the inventive apparatus and method is capable of repeatedlyperforming the steps necessary to seal the reclosable fastener zipperstrip to the web of flexible material while providing high manufacturingthroughout and low cycle times.

Generally, the apparatus and method utilize a reclosable fastener zipperstrip having airtight splotch seals fused in series along desiredlengths of the reclosable fastener zipper strip. The reclosable fastenerzipper strip is dispensed through a feeding mechanism and, when anoptical sensor detects one of the splotch seal portions of thereclosable fastener zipper strip, a desired length of the reclosablefastener zipper strip is advanced over an elevator platform. A knife isthen signaled to descend and sever the advanced portion of thereclosable fastener zipper strip, which is thus deposited onto theelevator platform.

As the selected portion of the reclosable fastener zipper strip is beingpositioned and deposited onto the elevator, the web of flexible film isbeing positioned above the platform. A sealing head is then positionedover the web of flexible film, while at the same time the elevatorplatform is driven upwardly so that the reclosable fastener zipper stripportion positioned thereon comes into contact with the web of flexiblefilm. The heat passing through the web of flexible film from the sealinghead is sufficient to seal the peripheral portions of the reclosablefastener zipper strip section to the web of flexible film, therebycreating an airtight seal between the reclosable fastener zipper stripportion and the web of flexible film.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a preferred embodiment of theapparatus of invention for sealing a reclosable fastener zipper strip toa web of flexible film;

FIG. 2 is a partial front perspective view of the apparatus of FIG. 1showing a pneumatically actuated elevator for placing the reclosablefastener zipper strip of the present invention against the web offlexible film;

FIG. 3 is a partial front perspective view of the apparatus of FIG. 1showing the pneumatically activated elevator of FIG. 2 having an openingin the center thereof for reception of a sealing head from above the webof flexible film;

FIG. 4 is a top perspective view of a sealing head and perforation diepositioned above the web of flexible film, with the sealing headpositioned to the side of the elevator and the perforation diepositioned over the elevator;

FIG. 5 is a top perspective view of a sealing head and perforation diepositioned above the web of flexible film, with the sealing headpositioned over the elevator and the perforation die positioned to theside of the elevator;

FIG. 6 is a side perspective view of the apparatus of FIG. 1;

FIG. 6A is a front plan view of the apparatus of FIG. 1;

FIG. 6B is a front perspective view of a computer used to control theapparatus of FIG. 1;

FIG. 7 is a front plan view of a bag manufactured using the presentinvention;

FIG. 8 is a side cutaway view of the bag of FIG. 7;

FIG. 9 is a front perspective view of the preferred embodiment of thereclosable fastener zipper strip of the present invention showing thefastener profiles of the first and second reclosable fastener zipperstrip;

FIG. 10 is a front perspective view of the reclosable fastener zipperstrip of FIG. 9 showing a series of interconnected reclosable fastenerzipper strip sections having splotch sections between each section; and

FIG. 11 is a front perspective view of a zipper tape application deviceapplying the reclosable fastener zipper strip to a web of flexiblematerial that is subsequently wound on a winder for later use in abagging machine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of inventive apparatus 120 (best shown in FIGS.1, 6 and 11) is capable of accurately sealing a multi-purpose reclosablezipper strip 100 to a flexible material web 110 in an airtight manner.Moreover, apparatus 120 is capable of repeatedly performing the stepsnecessary to seal the multi-purpose reclosable zipper strip 100 to theflexible material web 110 while providing high manufacturing throughoutand low cycle times.

The multi-purpose reclosable zipper strip 100 is preferably constructedof polyethylene and may include additives such as ethylene acetate tofacilitate easy sealing. The flexible material web 100 is alsopreferably constructed of polyethylene, but may be constructed of othercommonly known films, such as polyproplene or polyethylene terepthalate(Saran®), or any other material providing a sealing layer that iscompatible with the multi-purpose reclosable zipper strip 100.

As shown in FIG. 9, the multi-purpose reclosable zipper strip 100comprises (1) a continuous supply of first profile strip 100A; and (2) acontinuous supply of second profile strip 100C opposite the firstprofile strip 100A. The first profile strip 100A includes at least onerib 100B protruding from and along the length of the inner surface offirst profile strip 100A. The second profile strip 100C includes atleast two ribs 100D and 100E for sealably receiving rib 100B. Ribs 100Dand 100E protrude from and along the length of the inner surface ofsecond profile strip 100C. As shown in FIG. 10, a series of splotch sealportions 100F are fused along desired lengths of the first profile strip100A, the second profile strip 100C, and ribs 100B, 100D and 100E (shownin FIG. 9).

As seen in FIGS. 6 and 6A, the multi-purpose reclosable zipper strip 100is stored on fastener supply roll 130, from which it is fed throughapparatus 120 by a servometer 140, which controls the acceleration,speed and deceleration of the multi-purpose reclosable zipper strip100's movement through apparatus 120. The multi-purpose reclosablezipper strip 100 is wound through a series of dancer rollers 150 ondancer arm 160, which allows the multi-purpose reclosable zipper strip100 to be fed into a feeding mechanism 170 at the desired tension asshown in FIG. 2. In a preferred embodiment, as shown in FIG. 11, aphotosensor 162 reads the position of the dancer arm 160 and, when thedancer arm 160 is descended to a desired position, advances themulti-purpose reclosable zipper strip 100 using a nip drive 166.

The feeding mechanism 170 utilizes an optical sensor 180 to detect thepresence of the splotch seal portions 100F. The optical sensor 180detects the thickness of the multi-purpose reclosable zipper strip 100and is thus able to detect and distinguish each splotch seal portion100F because such portions are thinner than the remainder of themulti-purpose reclosable zipper strip 100. The splotch seal portions100F thus act as eye marks to indicate the position of the multi-purposereclosable zipper strip 100. In the preferred embodiment, the opticalsensor 180 utilizes a piezoelectric bridge to convert changes in opacityof the multi-purpose reclosable zipper strip 100 at the thinned portions(splotch seal sections 100F) to an electrical signal to advance themulti-purpose reclosable zipper strip 100 a desired length.

When optical sensor 180 detects one of the splotch seal portions 100F ofthe multi-purpose reclosable zipper strip 100, it signals belt tracks340 and 350 (see FIGS. 2 and 3), which utilize belt drive 360 to advancea desired length of the multi-purpose reclosable zipper strip 100 overelevator 230. Guillotine knife 370, driven by another servomotor 410, isthen signaled to descend and cut selected portion 420 of themulti-purpose reclosable zipper strip 100. Section 420 of themulti-purpose reclosable zipper strip 100 is thus positioned over anddeposited onto elevator 230. Both the operation of belt drive 360 andguillotine knife 370 can be sequenced using pneumatic control devicessuch as those manufactured by Matrix Technologies or by utilizing acomputer control system such as those manufactured by Allen Bradley.

As shown in FIG. 3, in a preferred embodiment, the top surface ofelevator 230 comprises a rectangular platform 240 for receiving section420 of the multi-purpose reclosable zipper strip 100. As the selectedportion 420 of the multi-purpose reclosable zipper strip 100 is beingpositioned and deposited onto platform 240 in the foregoing manner, theflexible material web 110 is being positioned above platform 240 asshown in FIG. 4. A series of eye marks is printed along one edge of theflexible material web 110 and is detected by a second optical sensor 190shown in FIG. 5. The flexible material web 110 is advanced throughapparatus 120 by a series of roll drivers 200, 202 (shown in FIGS. 2 and11), which are driven by a second servomotor 210 shown in FIG. 5. Thespeed of roll drivers 200, 202 is coordinated by the optical sensor 190and a computer 220 (shown in FIG. 6B), so that a desired portion of theflexible material web 110 is positioned over elevator 230 to receive theselected portion 420 of the multi-purpose reclosable zipper strip 100.

In one embodiment, the multi-purpose reclosable zipper strip 100 ismounted on a roller spool 130 (see FIG. 6). As the multi-purposereclosable zipper strip 100 is pulled through a series of dancer rollers150 (FIG. 11) mounted on dancer arm 160, roll drivers 200 pull themulti-purpose reclosable zipper strip 100 therethrough. When additionalmulti-purpose reclosable zipper strip 100 is pulled through dancerrollers 150, the upstream dancer arm 160 rises, causing coils 522 insprings 524 to stretch under tension (FIG. 6A). When the dancer arm 160reaches a preset position, the dancer arm 150 returns to an initiallower position. The coils 522 under tension pull the dancer arm 160 downto receive the multi-purpose reclosable zipper strip 100 being advancedthrough the three-loop dancer roll assembly 150 and the process is thenrepeated.

As shown in FIG. 3 according to one embodiment, elevator 230 iscontained within a hollow Lexan® pedestal 242 defining a central opening244 in which the platform 240 is positioned. As shown in FIGS. 4 and 5,a pair of rectangular ledges 248 and 249 are located at the top of thepedestal 242. When the selected portion of the flexible material 110 isfed into position over the platform 240, the selected portion of theflexible material 110 extends over and between the pair of rectangularledges 248 and 249.

As shown in FIGS. 4 and 5, a pneumatically controlled sealing head 270is mounted on block 280, which in turn is slidably mounted on shaft 291.As shown in FIG. 4, sealing head 270 and block 280 are positioned abovethe pair of rectangular ledges 248 and 249 and to the side of platform240. Following the deposit of section 420 of the multi-purposereclosable zipper strip 100 the multi-purpose reclosable zipper strip100 onto platform 240 and the positioning of the flexible material web110 above the platform 240, the block 280 is driven horizontally by anair cylinder 320 until the sealing head 270 is positioned above platform240 and, preferably, in contact with the flexible material web 110.Sealing head 270, which is preferably Teflon® coated, is then eitherheated to the desired sealing temperature or maintained at the desiredsealing temperature.

At the same time, elevator 230 is driven upwardly by shaft 400 untilplatform 240 (and the zipper tape portion 420 thereon) is in contactwith the flexible material web 110. The heat passing through theflexible material web 110 from the sealing head 270 is sufficient toseal the peripheral portions of zipper tape portion 420 of themulti-purpose reclosable zipper strip 100 (as seen in FIG. 10) to theflexible material web 110, thereby sealing the zipper tape portion 420positioned on the rectangular platform 240 to the flexible material web110 to create a fastener attached material web 112. Sealing head 270further aids in creating the seal, as shown in FIG. 7, by providing astable surface against which the elevator 230 can compress the flexiblematerial web 110 and the zipper tape portion 420.

The resulting seal 44 is airtight due to the construction of themulti-purpose reclosable zipper strip 100, which has thickened flanges30 (shown in FIG. 7) that melt and fill any gaps during sealing tofurther form the seal. Section 420 of the multi-purpose reclosablezipper strip 100 is also airtight throughout the zipper portions becauseof the unique construction of the zippers themselves, as disclosed inparent U.S. patent application Ser. No. 09/415,696, incorporated hereinby reference.

In one embodiment, a pneumatically controlled perforation knife 260 ismounted to block 280. When air cylinder 320 is actuated, perforationknife 260 descends downwardly so that perforation knife 260 perforatesflexible material web 110 between the pair of rectangular ledges 248 and249, which serve as an anvil against which the flexible material web 110is severed by the perforation knife 260. The air cylinder 320 thenretracts the perforation knife 260. In a preferred embodiment, sealinghead 270 and perforation knife 260 may be combined so that theperforation of the flexible material web 110 and the sealing of zippertape portion 420 may be accomplished simultaneously. Alternatively, thesealing head 270 can be moved into place over platform 240 after theflexible material web 110 has been severed by perforation knife 260. Inanother embodiment, fastener attached material web 112 is notperforated, but is fed and wound onto a winder 580 to create a zipperedroll stock 590 with the multi-purpose reclosable zipper strip 100already sealed on the flexible material web 110 for later use in abagging machine 510 (see FIG. 11).

While the present invention has been disclosed in terms of the preferredembodiments in order to facilitate better understanding of theinvention, it should be appreciated that the invention can be embodiedin various ways without departing from its basic principles. Therefore,the invention should be understood to include all possible embodimentsand modifications that do not depart from the invention as set out inthe appended claims.

1. An apparatus for sealing a portion of a zipper tape to a web section,the apparatus comprising: an elevator having a platform for receivingthe portion of zipper tape; means for depositing the portion of zippertape onto the platform; means for positioning the web section above theplatform; and a sealing head positioned over the web section for heatingthe web section, wherein the platform can be elevated towards the websection until the portion of zipper tape comes into contact with the websection to form a seal between at least a portion of the portion of thezipper tape and the web section.
 2. The apparatus of claim 1, whereinthe sealing head is in contact with the web section when the portion ofzipper tape comes into contact with the web section.
 3. The apparatus ofclaim 1, further comprising a cutter for perforating the web section. 4.The apparatus of claim 1, wherein the cutter comprises a knifepositioned above the web section.
 5. The apparatus of claim 1,whereinthe seal is substantially airtight.
 6. The apparatus of claim 1, whereinthe seal is substantially watertight.
 7. The apparatus of claim 1,wherein the zipper tape has at least one splotched portion and furthercomprising a sensor for detecting the splotched portion to obtain asignal, and a cutter for cutting said zipper tape in response to saidsignal to create the portion of zipper tape.